The qualities that make quantum computers so powerful also pose challenges around scalability. That’s particularly true for adding quantum bits, or qubits, to single systems. Complexity scales exponentially with the number of qubits – which is great for computation, but not so great for control. Issues such as noise, state preparation, and hardware and measurement complexities must be taken into account to optimize performance. At IonQ, we are making incredible headway by focusing on meaningful performance gains through networking technology.
One part of our vision to scale quantum computing involves the networking of multiple processors to create a stronger, shared system. Our recent acquisition of Entangled Networks aims to aid in the development of new tools and technology that incorporate modular architecture to distribute workloads across quantum processing units in order to increase computational speed and accuracy, as measured by our #AQ metric.
Quantum networking: A path to quantum computing at scale
IonQ’s founders, Jungsang Kim and Chris Monroe, are pioneers in the concept of modularity in quantum computing. This method of research is in our DNA, and we believe it offers the most promising path to scale by exchanging information across numerous quantum processing units (QPUs).
One of the important stages in modularity is the use of quantum photonic interconnects, which use quantum entanglement to conjoin qubits across different QPUs.Trapped ions are particularly amenable to this technology. The most convenient way to distribute entanglement is to use photons which are naturally emitted from our ions. IonQ’s barium ions have been specifically selected to, among other things, simplify this task. Unlike ytterbium ions which emit ultraviolet light, barium ions emit visible light which is easier to collect and transmit.
However, the relatively slow rate of information exchange between QPUs (i.e., low entanglement generation rates) is still a major barrier to scaling quantum computation.
As with classical supercomputers, which are made up of a network of multiple CPUs and GPUs, information processing in multi-QPU environments requires specialized protocols, including those around entanglement generation and the implementation of multi-qubit gates. These protocols are used to reduce bottlenecks caused by slow information exchange rates as well as other issues like fidelities.
With the acquisition of Entangled Networks, our multi-QPU protocols will optimize for performance with an easily integrated software package, further smoothing our path to implementation.
Quantum networking and trapped ions
IonQ’s ion-based technology has already proved to be the best performing qubit. With our recent announcement of #AQ25 on Aria, we once again pushed the limits of the state-of-the art in terms of quantum computational power. But that place where ion technology really shines is in the ability to interface with optical networks. Quantum architectures using superconducting qubits have clear networking challenges that will hamper their ability to scale. This is because superconducting qubits transmit information via microwaves. Transmitting microwaves directly requires extremely low (milli kelvin) temperature, otherwise the signal would be swamped by thermal noise. Converting single microwave photons to optical frequencies is currently an excruciatingly slow process, orders of magnitude improvements are needed to make it compatible with a quantum computer. In contrast, our trapped ions emit visible light which can be routed directly with optical fibers and optical switches.
Ultimately, we’re confident that multi-QPU platforms will speed quantum innovation in the future, and that our current team and technical approach have already demonstrated clear advantages over alternative methods. We're currently working on demonstrations of an early quantum network, and hope to continue to grow the size of that network over time.
IonQ recently discussed quantum networking progress, as well as its remaining challenges, at a Quantum Economic Development Consortium (QED-C) webinar on February 28. In a session called “Quantum Networking Testbeds,” we covered everything from the effective use of ions in quantum computing to single-system scalability, along with quantum information exchange and how best to maximize performance. (Check out the video, here!)
Be sure to stay tuned for more information about our networking breakthroughs, along with our performance milestones, including our recent #AQ25 achievement for the industry-leading Aria system.